I feel like you have probably seen balloon rockets before now. I can remember taking fifth-graders to the gym to set up lines for our balloon rockets over 30 years ago. We set up horizontal strings and students used the propulsion of air from a balloon to zip their “rockets” from one end of the line to the other.
Well, that is what is supposed to happen. In reality, a lot of different things happen. I knew this when I started thinking about trying balloon rockets as a STEM Challenge. I also felt like the traditional method would be too easy.
So, we tried balloon rockets with a twist!
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My little change in the requirements just meant changing one word. It is not a horizontal path for the rocket. It is vertical.
The Rocket Path
I hung pieces of string from the ceiling to the floor. Each team had their own string. The idea was that the rocket would start on the floor and then blast off- riding up that string to the top!
Sounds exciting, right?
First, we experimented with the balloons. Students blew up balloons (don’t worry, each students had their own balloon) and let them go.
I know it seems silly to let all of the students just chaotically blow up balloons and let them fly, but it actually serves a purpose. First of all, every single one of them wants to do this. So, this little fun time lets them get that off their minds. Secondly, I have a scientific purpose for this. The balloon propels forward with the rounded end first. Students might not know that. And they need to know this in order to build their rockets. A rocket loaded upside down is not going to travel ‘up’ the string path.
I know some of you are thinking that a released balloon does not travel in a straight path. It zigzags everywhere and this is true. But, when that balloon is attached to the string path it will only travel in the direction of the string!
Attaching
There are two things that must be attached in this challenge. The balloon must have a straw attached to it. The string must be ‘fed’ through the straw. This is what holds the rocket to the flight path string.
Both of these created problems to solve!
But, isn’t that why we love STEM so much!
Problem 1: Students attached the straw to the balloon with tape. This worked as long as the balloon was blown up. When the air was released the tape would “bunch up” and when the kids pulled the tape it would tear the balloon. So, students had to learn to carefully pull the tape off the balloon if they needed to.
Problem 2: Threading the string through straws was difficult- if the straw was very long. Short straws worked well. For students with extra long straws (like the one in the photo) I gave them an extra-large needle. The weight of the needle helped get the string through the straw.
This was all great until we added the next rule of the task…keep reading!
Make it Look Like a Rocket
Yes, I thought a rocket should look like a rocket. So, students had paper to make a rocket. They stuffed their balloon inside their rocket or attached the balloon to the rocket, and then tried having a lift off.
This, of course, added more problems to solve.
(And, I haven’t gotten to the part about having two balloons, yet!)
Problem 3: No matter what students used to make a rocket it added weight to the contraption. Some of their rockets were too heavy to lift off. This led to many iterations of the rocket in an attempt to pare down the size and have some success. In the above photo, the team started with a much larger version and finally narrowed it down to the cone-shaped model. This was still a little too heavy- likely due to the excess amount of tape used.
Two Balloons
Now, I had never planned to have the rockets use two balloons. However, students asked if they could try it. Well, why not? Maybe the extra balloon would help with the additional weight of each rocket.
Ah, you know what I am about to say. There were problems…
… to solve.
Problem 4: How do you get two balloons attached? Do you layer them on top of one another? Do you place them side by side? Think about it. If the two balloons are layered, the one on top blows its released air onto the top of the second one which makes it not rise. This style tended to rise a little, but not very far. The balloons that were placed side by side tended to work better- as long as the balloon nozzle was pointed to the ground. Teams that attached the balloons with the nozzle pointing horizontally to the ground found that their rocket traveled in a circle.
Problem 5: How do you get two balloons blown up, attach them without letting go too early, and let them go at the same time? Oh, my goodness, y’all. This was the most fun ever. Every team had a different style of countdown so the two holders of the balloons would release at the same time. I laughed a lot. Students might have been a little frustrated.
BALLOON PROBLEM 1: As I said already, every student had his or her own balloon. Teams had several different colors so they would always know which balloon belonged to each team member. As soon as teams began to attach balloons we stopped and invented rules about who could handle the balloons. Only the person blowing up the balloon could touch it while it was attached to the rocket. If two were attached then two team members blew up a balloon and then held their own balloon in place. One person could not hold two balloons.
BALLOON PROBLEM 2: Did I replace popped balloons? Yes. Balloons are going to pop.
BALLOON PROBLEM 3: Rules! I do have balloon rules! Students may not blow up balloons unless the balloon is going to be used immediately. They may not hold a balloon in their mouths. They must lay them down on their own paper towel when not in use. We wash our hands and clean off tables at the end of class.
The best part of this challenge is what happens with the frustration of not having successful rocket launches. Remember that photo above that was a cone-shaped rocket? A young man that was part of the team that built that rocket exclaimed to me, after trying over and over to get the rocket off the ground, “I cannot tell you how many times we have failed at this!” Did he stop trying? No, he did not. He dived right back into the challenge to try one more time.
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